The father and the son entered the tiger area _______ two doors were open at the time.
Suddenly five tigers appeared, one of which killed the father.
A. there B. which C. its D. whose
Gilbert wasn’t ______ the time this morning, so he was late for school.
A. involved in B. particular about C. linked to D. aware of
We should consider the professor’s advice _______ our school library provide more books on popular science.
A. that B. when C. which D. where
If Newton lived today, he would be surprised by what _______ in science and technology.
A. had discovered B. had been discovered
C. has discovered D. has been discovered
Pip agreed to give some piano lessons to the girl_______ for a generous gift from her mother.
A. in nature B. in return C. in turn D. in time
—Shall we go out for a walk?
— Sorry. This is not the right _______ to invite me. I am too tired to walk.
A. moment B. situation C. place D. condition
